This invention relates to a container, an apparatus and a method for continuously separating the platelets by applying centrifugal force to blood.
In recent years, blood taken out from human donors at blood centers or hospitals has often been separated into several blood components. A particular component is transfused to a patient who requires the component and another component is transfused to another patient who requires it. This is generally referred to as "component transfusion" as opposed to transfusing whole blood. Especially, platelets component is often transfused to a patient who has trouble with acute or chronic leukemia, cancer or infection or who is under a surgical operation, because the platelets adhere to the injured blood vessel wall and form an aggregation to prevent the blood from bleeding out.
In order to separate platelets component from blood in a relatively high degree of purity, a centrifugal force is applied to the blood at first to obtain platelet-rich plasma as supernatant, and then the platelet-rich plasma is further subjected to a centrifugal force so that the platelets component is separated. Such a method for the separation of platelets component is known, as disclosed in U.S. Pat. Nos. 4,010,894 and 4,146,172.
The process of continuously and hermetically treating blood, in which the blood is introduced into a processing chamber to which a centrifugal force is applied by rotating said chamber so that separated components, such as red blood cells, plasma and the other components, are discharged from the chamber, is important from the viewpoint of keeping the blood sterile and free from contaminents of the outside environment and also for using as small as possible amount of the blood taken out from donors at one time so that the risk like hypovolemia is reduced. It is also important to appropriately control the flow of the separated components, such as red blood cells, plasma and the other components, which are discharged from the processing chamber through pipes. Especially, the ratio of the quantities of the respective components must be precisely controlled. Unless such a control is appropriately effected, continuous separation would be almost impossible. According to a result of an experiment of the apparatus disclosed in the above-mentioned U.S. Pat. No. 4,010,894, it was confirmed that the continuous process was almost impossible. That is to say, some of the red blood cells which were precipitated in the first chamber without control were transferred to the second chamber.
According to a result of an experiment of the apparatus disclosed in the above-mentioned U.S. Pat. No. 4,146,172, it was confirmed the purity of platelets components obtained in the second chamber as the precipitate was about 92 percent, and the rest 6 percent was red blood cells and the rest 2 percent was white blood cells.
In addition, when experimenting with the apparatus disclosed in the above-mentioned U.S. Pat. No. 4,146,172, the inventors found that sometimes the blood flows backward. Blood is a suspension which consists of living cells, so that if a shearing force is exerted on the flow of the blood or if the blood flows backward, hemolysis or congelation of the blood can be caused.